1 /**
2 * Redistribution and use of this software and associated documentation
3 * ("Software"), with or without modification, are permitted provided
4 * that the following conditions are met:
5 *
6 * 1. Redistributions of source code must retain copyright
7 * statements and notices. Redistributions must also contain a
8 * copy of this document.
9 *
10 * 2. Redistributions in binary form must reproduce the
11 * above copyright notice, this list of conditions and the
12 * following disclaimer in the documentation and/or other
13 * materials provided with the distribution.
14 *
15 * 3. The name "Exolab" must not be used to endorse or promote
16 * products derived from this Software without prior written
17 * permission of Intalio, Inc. For written permission,
18 * please contact info@exolab.org.
19 *
20 * 4. Products derived from this Software may not be called "Exolab"
21 * nor may "Exolab" appear in their names without prior written
22 * permission of Intalio, Inc. Exolab is a registered
23 * trademark of Intalio, Inc.
24 *
25 * 5. Due credit should be given to the Exolab Project
26 * (http://www.exolab.org/).
27 *
28 * THIS SOFTWARE IS PROVIDED BY INTALIO, INC. AND CONTRIBUTORS
29 * ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT
30 * NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
31 * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
32 * INTALIO, INC. OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
33 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
34 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
35 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
36 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
37 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
38 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
39 * OF THE POSSIBILITY OF SUCH DAMAGE.
40 *
41 * Copyright 2002 (C) Intalio, Inc. All Rights Reserved.
42 *
43 * $Id$
44 */
45
46
47 package org.exolab.castor.mapping.handlers;
48
49 import org.exolab.castor.mapping.MapHandler;
50 import java.util.Enumeration;
51 import java.util.HashMap;
52 import java.util.Map;
53 import java.util.Iterator;
54
55 /**
56 * A Map handler for adding and retreiving key-value pairs from
57 * A map. A map handler is instantiated only once, must be thread
58 * safe and not use any synchronization.
59 *
60 * @author <a href="mailto:kvisco@intalio.com">Keith Visco</a>
61 * @version $Revision$ $Date: 2003-03-03 00:05:44 -0700 (Mon, 03 Mar 2003) $
62 */
63 public final class J2MapHandler
64 implements MapHandler
65 {
66
67 /**
68 * Creates a new Instance of the map represented by this MapHandler.
69 *
70 * @return the new map.
71 */
72 public Object create() {
73 return new HashMap();
74 } //-- create
75
76 /**
77 * Adds the given key-value pair to the map. Keys must be unique.
78 * Adding a key-value pair to the map, when an existing association
79 * for that key already exists will cause the existing association
80 * to be overwritten.
81 *
82 * The map is provided as a parameter and is returned as the return
83 * value if the returned map is a different object. That way the handler
84 * can create a new map if necessary.
85 *
86 * @param map the map, null if no map has been created yet.
87 * @param key the key for the object.
88 * @param object the object to add to the map.
89 * @return The map with the new object if a different
90 * instance than the <tt>map</tt> parameter, null otherwise
91 * @throws ClassCastException The MapHandler does not
92 * support maps of the given type.
93 */
94 public Object put( Object map, Object key, Object object )
95 throws ClassCastException
96 {
97 Object returnVal = null;
98 if (map == null) {
99 map = create();
100 returnVal = map;
101 }
102 ((Map)map).put(key, object);
103 return returnVal;
104 } //-- put
105
106
107 /**
108 * Returns an enumeration of all the objects in the Map.
109 *
110 * @param map The map instance for which to return the enumeration
111 * of elements for.
112 * @return An enumeration of all the elements in the Map.
113 * @throws ClassCastException The MapHandler does not
114 * support collections of this type
115 */
116 public Enumeration elements( Object map )
117 throws ClassCastException
118 {
119 if (map == null) map = create();
120 return new IteratorEnumerator(((Map)map).values().iterator());
121 } //-- elements
122
123 /**
124 * Returns an enumeration of all the keys in the Map.
125 *
126 * @param map The map instance for which to return the enumeration
127 * of keys.
128 * @return An enumeration of all the keys in the Map.
129 * @throws ClassCastException The MapHandler does not
130 * support collections of this type
131 */
132 public Enumeration keys( Object map )
133 throws ClassCastException
134 {
135 if (map == null) map = create();
136 return new IteratorEnumerator(((Map)map).keySet().iterator());
137 } //-- keys
138
139
140 /**
141 * Returns the number of elements (key-value) in the map.
142 *
143 * @param map the map.
144 * @return Number of key-value associations in the Map
145 * @throws ClassCastException The MapHandler does not
146 * support collections of the given type.
147 */
148 public int size( Object map )
149 throws ClassCastException
150 {
151 if (map == null) return 0;
152 return ((Map)map).size();
153 } //-- size
154
155
156 /**
157 * Clears the map of all key-value pairs.
158 *
159 * @param map the map to clear.
160 * @throws ClassCastException The MapHandler does not
161 * support collections of the given type.
162 */
163 public void clear( Object map)
164 throws ClassCastException
165 {
166 if (map == null) return;
167 ((Map)map).clear();
168 } //-- clear
169
170 /**
171 * Returns the object associated with the given key.
172 *
173 * @param map the map to return the object from.
174 * @param key the key for the object.
175 * @return the object associated with the given key, or null
176 * if no association was found in the given map.
177 * @throws ClassCastException The MapHandler does not
178 * support maps of the given type.
179 */
180 public Object get( Object map, Object key)
181 throws ClassCastException
182 {
183 if (map == null) return null;
184 return ((Map)map).get(key);
185 } //-- get
186
187 /**
188 * Enumerator for an iterator.
189 */
190 static final class IteratorEnumerator
191 implements Enumeration
192 {
193
194 private final Iterator _iterator;
195
196 IteratorEnumerator( Iterator iterator )
197 {
198 _iterator = iterator;
199 }
200
201 public boolean hasMoreElements()
202 {
203 return _iterator.hasNext();
204 }
205
206 public Object nextElement()
207 {
208 return _iterator.next();
209 }
210
211 }
212
213 } //-- J2MapHandler
214
215
216